by: Heather Smith Thomas

Most cows “clean“ soon after calving, shedding the placental membranes within 2 to 12 hours. If it takes longer than 12 hours, we usually call it a retained placenta or retained fetal membranes. Dr. Bill Lias (Interstate Vet Clinic, Brandon, SD) says there are a number of reasons a cow might not clean, including anything that would cause her to calve early -- an abortion, an infection, a toxic insult, a premature calf, twins, etc.

“We almost always see retained placenta in those situations. Nutritional deficiencies can also be a cause. With dairy cows, especially, we know that the cows that are low on calcium or have milk fever have a much higher incidence. Retained placenta has also been linked to vitamin A deficiency, selenium deficiency, and sometimes copper. There may be more nutritional causes than we know,“ says Lias.

“If producers start to see more than a few incidences of retained placenta, without the common and logical causes (like abortion, twins, dystocia, an induced calving, etc.) then they should have their nutritional program evaluated. If you are having normal births but a higher than normal incidence of retained placenta, that should be reason to consult with a nutritionist and see if the vitamin and mineral levels in the feed are where they need to be.“ It would be wise to take some feed samples and perhaps also some blood samples from the cows to check their mineral status.

Other causes for an occasional retained placenta would be cows that are very thin or very fat. Having your cows in proper body condition, with good nutrition and good health are the best prevention.

Any cow that retains her placenta should be closely monitored to make sure she does not develop an infection. Often no treatment is required; the membranes will come away on their own within a few days (sometimes up to a week or 10 days) and the cow will be fine, but occasionally a retained placenta can lead to serious infection. In those situations the cow will go off feed and have a fever, and she will need treatment.

In earlier days, veterinarians recommended removing the placenta if a cow didn't clean within a day or so, but research has shown that it's better to just leave them alone. “Back in the day when I graduated from veterinary school, the standard practice was to try to remove those placentas, but in recent years we've discovered that is not the way to go for the health of the cow and her future fertility; it's best to just leave those cows alone,“ says Lias.

“I still get calls occasionally from people wanting me to come clean a cow, and I have to tell them that we don't do that anymore. There is always risk for damage when we try to remove those membranes. There are attachment sites where the placenta interfaces with the uterine lining--the caruncles in the uterus attach to the cotyledons of the placenta. A cow has a set number of caruncles and if any of those are torn off they do not regenerate. We know that there are a certain number of these that are required to support a pregnancy, so it's not a good idea to manually try to remove the placenta and risk damage to those caruncles,“ he says.

“We also run the risk of introducing more contaminants into the uterus when we try to remove the placenta. The standard of care today, and our recommendation to producers, is to leave those cows alone, and the majority of them do just fine. You do want to keep that cow in a clean, dry environment until she does shed those membranes, however. Some times of year, that's a challenge,“ he says.

Often the cow is better off out in a pasture, moving around, rather than confined in a dirty corral. “The main complicating factor is the introduction of infection when those membranes are hanging out and she's lying down in manure or mud,“ says Lais. Those membranes can act as a wick to bring pathogens right into the uterus.

“Our best advice to producers is to leave the cow alone, in a clean place, and watch her. Most of these cows will be fine, but if she starts acting sick they should consult a veterinarian. The cow may need to be put on systemic antibiotics, and the veterinarian may consider a lavage (flushing the debris out of the uterus with antiseptic fluids). This would be a decision for the veterinarian, based on physical findings.“

In the past, many cows with retained placenta were also treated with oxytocin or drugs like Lutalyse and prostaglandin after calving. “Most of the data today has shown that these treatments are really not very helpful. The bovine uterus is no longer receptive to oxytocin about 24 hours after calving, and it has not shown to have much benefit in terms of helping a cow clean,“ says Lias.

If the cow remains normal, with good appetite, she doesn't need treatment, even if it takes her a week or longer to clean. “If they don't get sick, those cows do fine and will rebreed on schedule. Cows are very hardy animals!“

The uterus can generally handle a local mild infection and clean itself out, but if the infection goes systemic the cow will definitely need some help.

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